Orr won his first Stanley Cup in 1970 and it was with a flourish only he could manage. His Bruins, a team that hadn't won the Cup in 29 years, were attempting to sweep the St. Louis Blues in the finals. Game four went into overtime. Orr had taken Derek Sanderson's pass from the corner and flashed in front of the net to bury it behind Blues goalie Glenn Hall. As Orr streaked past the net, he was upended by defenseman Noel Picard. Orr jumped, or flew, as he saw the puck beat Hall and the arena erupted. The resulting picture, with Orr's arms raised and his body floating three feet above the ice, was in newspapers and magazines around the world. Orr was awarded the Conn Smythe Trophy as the playoffs' most valuable player, an award he would win when Boston again won the title in 1972, again with the Cup-winning goal coming off Orr's stick.

Orr revolutionized the sport with his scoring ability and playmaking from the blue line. Other defenders, beginning as early as Lester Patrick in the nascent days of the game, had been offensive threats, but Orr dominated. He won two scoring titles, the only defender to accomplish that feat, and had career season highs of 46 goals and 102 assists. More than just statistics, Orr had the ability to control the game, to take over. He had the speed to float away from defenders and also to recover should he lose possession or get caught on a rush. Often, odd-man rushes in the other team's favour were reversed by his effortless strides. Some argued that he wasn't defensively sound, but hockey people rejected these claims.

For eight consecutive seasons Orr won the Norris Trophy as the best defenseman and three times he was the league's most valuable player to collect the Hart Trophy. Orr's plus-minus rating when he was at his best was untouchable at plus-124 in 1970-71, when he scored 139 points.

At the beginning of the 1971-72 season, Orr signed a contract that guaranteed him $200,000 per season over five years. It was the first $1 million deal in hockey and Orr's agent predicted at the time that Orr would someday own part of the team if he continued to star for Boston. As it turned out, when it came time to negotiate a new contract prior to the 1976-77 season, the Bruins did offer Orr a piece of the ownership but the star player said his agent never informed him of the proposed deal. Orr, who had struggled with his left knee and played only 10 games in 1975-76, felt as though Boston no longer wanted him and signed instead with the Chicago Black Hawks. Once considered the saviour and then the hero of the rejuvenated Bruins, Orr left the team that had been a part of his career since he was a teen in Parry Sound.

Orr took advantage of a chance to play in a major international competition - the 1976 Canada Cup - when Chicago management gave him permission to play. Having missed all of the Summit Series, the Canada Cup proved to be Orr's only major appearance in a competition against the best the world had to offer.